The present invention relates generally to power distribution systems, and more particularly, to sensors and systems for estimating characteristics of a power line.
Electrical energy plays a central role in industrialized societies. The reliability of electric power systems is a critical factor in the planning, design and operation of power distribution systems. To ensure reliability, automated, real-time control of the system is desirable to allow for rapid respond to the actual demand of electricity and any unforeseen contingencies (equipment outages).
Modernized power distribution networks typically utilize energy control centers to monitor and regulate network operation. Although these centers have greatly advanced in technology, their basic control objectives of economy and security remain the same. The economic goal is to minimize the cost of supplying the electrical demand. The security goal is directed to the minimum requirements for reliability and quality of service. Electric utilities desire measurements of line voltage and current to allow for automated customer billing, load and reliability monitoring, and for real time control of the system.
Traditionally, current measurements with accuracies to within 0.3% or less are desired for customer billing while less accurate measurements (1 to 10%) typically suffice for other functions such as fault isolation and system control. However, in the past, many electric utilities typically employed highly accurate and very expensive current and or voltage transformers to perform measurements requiring strict accuracy as well as well as measurements to support functions such as fault isolation that require less accuracy. System inefficiencies are further exaggerated by the fact that distribution lines must be cut to accommodate the installation of conventional current transformers, which in most cases, is labor intensive.
Recently, the cost of measuring voltage and current in the 1 to 10% accuracy range in electrical power distribution feeders has decreased. Presently, line post current sensors that include a sensing element permanently embedded within an insulator are used as a less expensive and easier to install alternative to current transformers. Some other current sensors are connected at high voltage potential but the output signals must have isolation from the high voltage; frequently this is done via radio or fiber optic communications. There are also economical, temporary current sensors that are held in place with hot line sticks or are simply hung over the line. The installation time and effort of most new measuring devices is less than the time Be and effort to install current transformers. However, electric utility personnel are very familiar with the traditional current transformers and adoption of new devices within the industry has been gradual.
Therefore, it would be advantageous to provide a compact, lightweight sensing device that measures at least one operating characteristic of an overhead power line that may be readily attached and removed from a power line. The sensing device should preferably be suitable for economy of manufacture and durable to minimize operation and maintenance cost.
In one aspect of the present invention, a system for measuring at least one characteristic of a power line is supported by a power line pole and includes a pin having one end coupled to the pole and a second end adapted to engage a sensor. The sensor measures at least one characteristic of the power line. An insulator coupled to the second end of the pin, supports the power line in a conventional manner.
In another aspect of the present invention, a method for measuring at least one characteristic of a power line supported by a power line pole includes engaging a sensor with a first end of a pin, coupling an insulator to the first end of the pin, coupling a second end of the pin to the power pole, coupling the power line to the insulator, and measuring a characteristic of the power line.